What type of refrigerants does the EPA consider as natural refrigerants?

The correct answer highlights the types of refrigerants that the EPA recognizes as natural refrigerants, which include ammonia, carbon dioxide (CO2), and hydrocarbons. These substances are considered natural refrigerants because they have low environmental impact in terms of ozone depletion potential (ODP) and global warming potential (GWP).

Ammonia is a well-established refrigerant that is used in commercial and industrial applications, particularly in large-scale refrigeration systems. Carbon dioxide is gaining popularity as a refrigerant due to its low GWP and non-flammability, making it suitable for various applications including supermarket refrigeration. Hydrocarbons such as propane and isobutane are also recognized for their low environmental impact and are used in smaller refrigeration systems.

In contrast, the other options contain substances not classified as natural refrigerants. Chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs) are synthetic chemicals that have been widely restricted due to their negative effects on the ozone layer and high global warming potential, rendering them unsuitable for environmentally friendly refrigeration practices. Hydrogen and chlorine-based compounds are not recognized as refrigerants within the context of natural refrigerants either, as they do not fit the criteria for low environmental impact.

Thus